CN108346739A - A kind of Ge-Sb-C phase-change storage materials, preparation method and application - Google Patents
A kind of Ge-Sb-C phase-change storage materials, preparation method and application Download PDFInfo
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- CN108346739A CN108346739A CN201810097825.8A CN201810097825A CN108346739A CN 108346739 A CN108346739 A CN 108346739A CN 201810097825 A CN201810097825 A CN 201810097825A CN 108346739 A CN108346739 A CN 108346739A
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- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices without a potential-jump barrier or surface barrier, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/801—Constructional details of multistable switching devices
- H10N70/881—Switching materials
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices without a potential-jump barrier or surface barrier, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/011—Manufacture or treatment of multistable switching devices
- H10N70/021—Formation of the switching material, e.g. layer deposition
- H10N70/026—Formation of the switching material, e.g. layer deposition by physical vapor deposition, e.g. sputtering
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices without a potential-jump barrier or surface barrier, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/011—Manufacture or treatment of multistable switching devices
- H10N70/041—Modification of the switching material, e.g. post-treatment, doping
- H10N70/043—Modification of the switching material, e.g. post-treatment, doping by implantation
Abstract
The invention belongs to microelectronics technologies, and in particular to a kind of Ge Sb C phase-change storage materials, preparation method and application.The Ge Sb C New-type phase change storage materials of the present invention, chemical composition general formula (GeiSbj)100‑xCx, wherein x, i, j indicate atomic percent, 0 ＜ x ＜, 15,0 ＜ i≤50,50≤j ＜ 100, i+j=100.Compared with prior art, a kind of Ge Sb C phase-change storage materials of the invention before phase change after variable density reduce so that the stress that is generated after phase transformation reduces, and device cycle performance improves；In the present invention simultaneously, the Ge Sb C phase-change storage material phase transition temperatures are improved significantly, thermal stability enhancing, data retention enhancing；In addition, the crystalline resistance rate of the Ge Sb C phase-change storage materials increases, the RESET electric currents of device reduce, and operate lower power consumption.
Description
Technical field
The invention belongs to microelectronics technologies, and in particular to a kind of Ge-Sb-C phase-change storage materials, preparation method and
Using.
Background technology
Phase transition storage (PCRAM) be based on phase-change storage material (mainly chalcogenide compound) crystal and it is noncrystal it
Between rapid translating realize the storage of " 0 " and " 1 ".In phase-change memory cell, it is only necessary to utilize narrow spaces, an amplitude
Electric pulse operate on it (RESET operation), crystalline phase-change storage material will melt rapid cooling, be changed into amorphous state, from
And it realizes from low resistance state " 0 " to the quick resistive of high-resistance state " 1 ".Conversely, applying wide pulse width, low amplitude value to device
Electric pulse (SET operation), amorphous state phase-change storage material will crystallize phase transformation, return to low resistance state.Phase transition storage has read-write
The advantages that speed is fast, storage density is high, mutually compatible with traditional cmos process.
(Ge2Sb2Te5) GST is widely studied as traditional phase-change storage material and in the industrialization of phase transition storage
It is middle to be applied, but research shows that the presence of sulphur series elements Te will produce some seondary effects, influence the performance (Krusin- of device
Elbaum,L.,et al.,Evidence for segregation of Te in Ge2Sb2Te5films:Effect on
the“phase-change”stress.Applied Physics Letters,2007.90(14):p.141902).First, Te
The diffusion coefficient of element is higher, is spread easily in phase-change memory cell and interacts with neighbouring Te elements and lead to Te simple substance
Phase separation；Meanwhile Te elements easily assemble generation stress in grain boundaries, to influence the cycling durable performance of device；It is most important
It is that, due to the intrinsic vacancy there are 10% or so in crystalline state GST, during mutually becoming amorphous, these vacancy can assemble
At 16%~17% or so amorphous cavity, so that the volume differences (density contrast) after before phase change reach 6%~7%, shadow
Ring its service life (Njoroge, W.K., H.-W. as deviceand M.Wuttig,Density
changes upon crystallization of Ge2Sb2.04Te4.74films.Journal of Vacuum Science&
Technology A:Vacuum,Surfaces,and Films,2002.20(1):p.230-233).High density storage in this
A problem is with regard to even more serious, because in three-dimensional high-density storage, the stress that device density variation generates will be applied, to
Cause the failure of storage array.
And in Ge-Sb materials, the missing of Te elements is expected to solve the above problems.It is accounted in addition, Ge-Sb belongs to grain growth
Leading type material, crystallization rate is quickly；And component ratio is Ge15Sb85Phase transition temperature be 250 DEG C of (Zalden, P., et
al.,Atomic structure of amorphous and crystallized Ge15Sb85.Journal of Applied
Physics,2010.107(10):P.104312), high than phase transition temperature (156 DEG C) of traditional phase-change storage material GST, energy
Its amorphous state thermal stability is effectively improved to improve the data storage capacities of device, while reducing the heat string between storage unit
It disturbs；And in crystalline state Ge-Sb be not present intrinsic vacancy, therefore before phase change after variable density ratio GST it is small.But Ge-Sb is in phase
The PHASE SEPARATION that will appear rich Ge and richness Sb during becoming, influences the recycling performance of device.In order to further decrease Ge-Sb
Variable density after before phase change promotes the performance of Ge-Sb, it is therefore desirable to modification is doped to this.
Invention content
For the disadvantages described above or Improvement requirement of the prior art, the present invention provides a kind of Ge-Sb-C phase-change storage materials,
Preparation method and application, its object is to by the way that carbon is introduced in the Ge-Sb phase-change storage materials of the prior art, phase
It obtains a kind of Ge-Sb-C phase-change storage materials for phase transition storage with answering, phase-change storage material can be reduced in phase
Become front and back variable density, improve phase-change storage material thermal stability, improve the cycling durable performance of memory device, reduces memory
Operation power consumption of part etc..
To achieve the above object, according to one aspect of the present invention, a kind of Ge-Sb-C phase-change storage materials are provided,
Chemical composition general formula is (GeiSbj)100-xCx, wherein x, i, j are atomic percent, wherein 0 ＜ x ＜ 15,0 ＜ i≤50,50
≤ j ＜ 100, i+j=100.
Preferably, the phase-change storage material, 0 ＜ x ＜, 6,0 ＜ i≤20,80≤j ＜ 100, i+j=100.
Preferably, C atoms are present in Ge-Sb interstitial voids in the Ge-Sb-C phase-change storage materials, and and Ge-Sb
Form chemical bond.
Preferably, the Ge-Sb-C phase-change storage materials are Ge-Sb-C phase change film materials.
Preferably, the thickness of the film is 20-200nm.
Preferably, the Ge-Sb-C phase-change storage materials control the phase change memory material by controlling the incorporation content of C
The phase transition temperature and resistivity of material.
Preferably, the resistivity of the high-impedance state of the Ge-Sb-C phase-change storage materials is at least 100 times of low resistance state.
Other side according to the invention provides a kind of preparation method of the phase-change storage material, is magnetic
Control sputtering method, chemical vapour deposition technique, atomic layer deposition method, galvanoplastic or electron-beam vapor deposition method.
Preferably, the preparation method is magnetron sputtering method, and specific magnetron sputtering mode is in following four mode
Any one：(1) C, Ge and Sb target co-sputtering；(2) C and GeiSbjCosputtering；(3) Ge after C dopingiSbjAlloys target sputters
(4) graphite flake is directly placed at GeiSbjSputtering is doped on alloy target material.
Other side according to the invention provides a kind of Ge-Sb-C phase-change storage materials in phase transition storage
In application.
In general, through the invention it is contemplated above technical scheme is compared with the prior art, can obtain down and show
Beneficial effect：
Compared with Ge-Sb phase-change storage materials undoped in the prior art, Ge-Sb-C phase-change materials of the invention
In, C is atom doped in Ge-Sb interstitial voids, and forms tetrahedron center in amorphous state and improve atom packing efficiency, Ge-
Sb-C phase-change storage materials before phase change after variable density reduce so that the stress that is generated after phase transformation reduces, and device cycle is durable
Performance improves；In the present invention simultaneously, the phase transition temperature of the Ge-Sb-C phase-change storage materials is improved significantly, and heat is steady
Qualitative enhancing enhances to the data retention of device；In addition, the crystalline resistance rate liter of the Ge-Sb-C phase-change storage materials
The RESET electric currents of height, device reduce, and operate lower power consumption.
Description of the drawings
Fig. 1 is the Ge-Sb-C phase-change storage materials of difference C doping contents of the invention and the Ge-Sb phase transformations for comparative example 1
The front and back X ray reflection rate pattern of storage material annealing.Crystalline state sample is annealed 10min at 250 DEG C.
Fig. 2 is the Ge-Sb-C phase-change storage materials with the AFM difference C doping contents of the invention measured and is used for comparative example 1
The annealing that is characterized with thickness of Ge-Sb phase-change storage materials before and after volume (density) variation with C doping contents change curve.
Crystalline state sample is annealed 10min at 250 DEG C.
Fig. 3 is the Ge-Sb-C phase-change storage materials of different C contents of the invention and the Ge-Sb phase change memories for comparative example 1
The In-situ resistance rate of material and the relation curve of annealing temperature, wherein heating rate are 5 DEG C/min.
Fig. 4 be in the present invention with first-principles calculations when C doping contents be 5% amorphous state Ge-Sb-C bond distance,
Bond angle and ligancy situation.
Fig. 5 is the amorphous state Ge-Sb-C phase transformation materials for being 5% when C doping contents with first-principles calculations in the present invention
Super born of the same parents' model of material.
Fig. 6 is in the present invention with C in the Ge-Sb-C phase-change storage materials of the different C doping contents of first-principles calculations
The formational situation of chain.
Specific implementation mode
In order to make the purpose , technical scheme and advantage of the present invention be clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.As long as in addition, technical characteristic involved in the various embodiments of the present invention described below
It does not constitute a conflict with each other and can be combined with each other.
The present invention provides a kind of Ge-Sb-C phase-change storage materials, for C is introduced to Ge-Sb phase-change storage material bodies
It is obtained in system, chemical composition general formula is (GeiSbj)100-xCx, in GeiSbjC is adulterated on the basis of material, obtains Ge-Sb-C
Phase-change storage material.X, i, j are atomic percent, wherein 0 ＜ x ＜, 15,0 ＜ i≤50,50≤j ＜ 100, i+j=100.Compared with
Good, the value range of the x is 0 ＜ x ＜ 6, and the value range of further preferably 2 ＜ x ＜ 6, i are taking for 0 ＜ i≤20, j
It is worth ranging from 80≤x ＜ 100, and i+j=100.In the Ge-Sb-C phase-change storage materials, the C atoms of incorporation are in Ge-Sb crystalline substances
The interstitial site of lattice, and with Ge, Sb at chemical bond.As a preferred option, the Ge-Sb-C phase-change storage materials are Ge-
Sb-C phase change film materials.Preferably, the thickness of Ge-Sb-C phase change film materials is 20nm-200nm.
The institute that the front and back change in film thickness of annealing is measured with AFM is measured with annealing temperature variation relation for In-situ resistance rate
Ge-Sb-C phase change film material thickness is stated in 200nm or so.The Ge-Sb-C phase-change thin films for x-ray albedo measurement
Material thickness is in 20nm or so.Crystalline substance for x-ray albedo measurement and AFM the Ge-Sb-C phase change film materials measured
Aspect product carry out annealing crystallization at 250 DEG C.The resistivity of the high-impedance state of the Ge-Sb-C phase-change storage materials is at least low-resistance
100 times of state resistivity.The Ge-Sb-C phase-change storage materials mix the content of C to control the phase change memory by control
Phase transition temperature, the resistivity of material.The phase transition temperature of the Ge-Sb-C phase-change storage materials is improved significantly compared with Ge-Sb.
The crystalline resistance rate of the Ge-Sb-C phase-change storage materials is improved compared with Ge-Sb.Mix the C's of different atomic percentage contents
Ge-Sb-C phase-change storage materials before phase change after variable density can be down to 2% or so.When the atomic percentage content of doping C is higher than
When 6%, first-principles calculations observed the formation of C chains, so C dopings also should not be too high.
The present invention provides a kind of preparation method of the Ge-Sb-C phase-change storage materials for phase transition storage, preparation sides
Method includes magnetron sputtering method, chemical vapour deposition technique, atomic layer deposition method, galvanoplastic, electron-beam vapor deposition method etc..Wherein magnetic control splashes
Shooting method preparation is the most flexible, and C, Ge, Sb target co-sputtering may be used, can also use C and GeiSbjCosputtering can also be adopted
Ge after being adulterated with CiSbjAlloys target sputters, and can also use graphite flake being directly placed at GeiSbjAlloy target material is enterprising
Row doping sputtering, these methods can prepare the Ge-Sb-C phase-change storage materials of the present invention according to the proportioning of chemical general formula.
Ge-Sb-C phase-change storage materials mature preparation process of the present invention, it is easy to accomplish with existing microelectronic process engineering
Compatible, Ge-Sb-C phase-change storage materials of the invention not only inherit the advantages that Sb base phase-change storage material phase velocities are fast, together
When also reduce before phase change after variable density, promote the cycling durable performance of device, Ge-Sb-C phase change memory materials of the invention
Material also has higher phase transition temperature and higher crystalline resistance rate, is conducive to improve data retention, reduces power consumption.
It is embodiment below：
Embodiment 1
The chemical composition general formula of the nanometer Ge-Sb-C phase change film materials for phase transition storage prepared in the present embodiment
For (GS)100-xCx, wherein GS represents Ge15Sb85, x=2.66 in the present embodiment.
Ge-Sb-C nano film materials are made using magnetron sputtering method；High-purity argon gas is passed through when preparation as sputter gas,
Sputtering pressure is 0.5pa, Ge15Sb85Target uses DC power supply, power 30W, in Ge15Sb85It is placed at the etched rings of target
The graphite flake of a piece of 1cm*1cm sizes is doped sputtering.Specific preparation method includes the following steps：
1. choosing the SiO that size is 1cm*1cm2/ Si (100) substrate, cleaning surface, the back side, removal dust granule, organic
And inorganic impurity.
A) by SiO2/ Si (100) substrate is rinsed in acetone soln with the power ultrasonic 10 minutes of 40W, deionized water；
B) by treated substrate in ethanol solution with the power ultrasonic of 40w 10 minutes, deionized water is rinsed, high-purity
N2Surface and the back side are done in air-blowing, obtain substrate to be sputtered.
2. being prepared (GS) using d.c. sputtering method97.34C2.66Prepare before film.
A) in Ge15Sb85The graphite flake of a piece of 1cm*1cm sizes is put at target material surface etched rings；
B) Ge for being placed with piece of graphite piece is installed15Sb85The purity of target, target reaches 99.99% (atomic percent),
And base vacuum is evacuated to 10-4pa；
C) it uses high-purity Ar gas as sputter gas, sets Ar steady air currents and be adjusted to as 10sccm, and by sputtering pressure
The distance 150mm of 0.5pa, target and substrate；
D) DC sputtering power power is set as 30W.
3. the method for magnetron sputtering is prepared (GS)97.34C2.66Nano phase change thin-film material.
A) space base support is rotated into Ge15Sb85Target position opens Ge15Sb85The baffle of target position carries out pre-sputtering 5-10min, clearly
Clean target material surface；
b)Ge15Sb85After the completion of target material surface cleaning, Ge is closed15Sb85The baffle of target position rotates to substrate to be sputtered
Ge15Sb85Target position opens Ge15Sb85Target position baffle, according to the sputtering time of setting, the Ge-Sb-C for starting to sputter different-thickness is thin
Film.When sputtering time is 2min, (GS) that is prepared97.34C2.66Film thickness is 20nm or so, is used for X ray reflection rate
It measures；When sputtering time is 15min, (GS) that is prepared97.34C2.66Film thickness is 200nm or so, for electricity in situ
The annealing of resistance rate measures and AFM is measured.Film thickness is controlled by sputtering time, in Ge15Sb85When putting piece of graphite piece on target
The sputter rate of film is 4.6s/nm.Through x-ray photoelectron spectroscopy (XPS) quantitative analysis, the change of the present embodiment thin-film material
It is (GS) to learn composition formula97.34C2.66。
Embodiment 2
The chemical composition general formula of the nano phase change thin-film material for phase transition storage prepared in the present embodiment is
(GS)100-xCx, x=4.98 in the present embodiment.
Ge-Sb-C nano film materials are made using magnetron sputtering method；High-purity argon gas is passed through when preparation as sputter gas,
Sputtering pressure is 0.5pa, Ge15Sb85Target uses DC power supply, power 30W, in Ge15Sb85It is placed at the etched rings of target
The graphite flake of two panels 1cm*1cm sizes is doped sputtering.Specific preparation method includes the following steps：
1. choosing the SiO that size is 1cm*1cm2/ Si (100) substrate, cleaning surface, the back side, removal dust granule, organic
And inorganic impurity.
A) by SiO2/ Si (100) substrate is rinsed in acetone soln with the power ultrasonic 10 minutes of 40W, deionized water；
B) by treated substrate in ethanol solution with the power ultrasonic of 40w 10 minutes, deionized water is rinsed, high-purity
N2Surface and the back side are done in air-blowing, obtain substrate to be sputtered.
2. being prepared (GS) using d.c. sputtering method95.02C4.98Prepare before film.
A) in Ge15Sb85The graphite flake of two panels 1cm*1cm sizes is put at target material surface etched rings；
B) Ge for being placed with two panels graphite flake is installed15Sb85The purity of target, target reaches 99.99% (atomic percent),
And base vacuum is evacuated to 10-4pa；
C) it uses high-purity Ar gas as sputter gas, sets Ar steady air currents and be adjusted to as 10sccm, and by sputtering pressure
The distance 150mm of 0.5pa, target and substrate；
D) DC sputtering power power is set as 30W.
3. the method for magnetron sputtering is prepared (GS)95.02C4.98Nano phase change thin-film material.
A) space base support is rotated into Ge15Sb85Target position opens Ge15Sb85The baffle of target position carries out pre-sputtering 5-10min, clearly
Clean target material surface；
b)Ge15Sb85After the completion of target material surface cleaning, Ge is closed15Sb85The baffle of target position rotates to substrate to be sputtered
Ge15Sb85Target position opens Ge15Sb85Target position baffle, according to the sputtering time of setting, the Ge-Sb-C for starting to sputter different-thickness is thin
Film.When sputtering time is 2min, (GS) that is prepared97.34C2.66Film thickness is 20nm or so, is used for X ray reflection rate
It measures；When sputtering time is 20min, (GS) that is prepared95.02C4.98Film thickness is 200nm or so, for electricity in situ
The annealing of resistance rate measures and AFM is measured.Film thickness is controlled by sputtering time, in Ge15Sb85When putting two panels graphite flake on target
The sputter rate of film is 5.8s/nm.Through x-ray photoelectron spectroscopy (XPS) quantitative analysis, the change of the present embodiment thin-film material
It is (GS) to learn composition formula95.02C4.98。
Embodiment 3
The chemical composition general formula of the nano phase change thin-film material for phase transition storage prepared in the present embodiment is
(GS)100-xCx, x=5.75 in the present embodiment.
Ge-Sb-C nano film materials are made using magnetron sputtering method；High-purity argon gas is passed through when preparation as sputter gas,
Sputtering pressure is 0.5pa, Ge15Sb85Target uses DC power supply, power 30W, in Ge15Sb85It is placed at the etched rings of target
The graphite flake of three pieces 1cm*1cm sizes is doped sputtering.Specific preparation method includes the following steps：
1. choosing the SiO that size is 1cm*1cm2/ Si (100) substrate, cleaning surface, the back side, removal dust granule, organic
And inorganic impurity.
A) by SiO2/ Si (100) substrate is rinsed in acetone soln with the power ultrasonic 10 minutes of 40W, deionized water；
B) by treated substrate in ethanol solution with the power ultrasonic of 40w 10 minutes, deionized water is rinsed, high-purity
N2Surface and the back side are done in air-blowing, obtain substrate to be sputtered.
2. being prepared (GS) using d.c. sputtering method94.25C5.75Prepare before film.
A) in Ge15Sb85The graphite flake of three pieces 1cm*1cm sizes is put at target material surface etched rings；
B) Ge for being placed with three pieces graphite flake is installed15Sb85The purity of target, target reaches 99.99% (atomic percent),
And base vacuum is evacuated to 10-4pa；
C) it uses high-purity Ar gas as sputter gas, sets Ar steady air currents and be adjusted to as 10sccm, and by sputtering pressure
The distance 150mm of 0.5pa, target and substrate；
D) DC sputtering power power is set as 30W.
3. the method for magnetron sputtering is prepared (GS)94.25C5.75Nano phase change thin-film material.
A) space base support is rotated into Ge15Sb85Target position opens Ge15Sb85The baffle of target position carries out pre-sputtering 5-10min, clearly
Clean target material surface；
b)Ge15Sb85After the completion of target material surface cleaning, Ge is closed15Sb85The baffle of target position rotates to substrate to be sputtered
Ge15Sb85Target position opens Ge15Sb85Target position baffle, according to the sputtering time of setting, the Ge-Sb-C for starting to sputter different-thickness is thin
Film.When sputtering time is 3min, (GS) that is prepared94.25C5.75Film thickness is 20nm or so, is used for X ray reflection rate
It measures；When sputtering time is 30min, (GS) that is prepared94.25C5.75Film thickness is 200nm or so, for electricity in situ
The annealing of resistance rate measures and AFM is measured.Film thickness is controlled by sputtering time, in Ge15Sb85When putting three pieces graphite flake on target
The sputter rate of film is 8.6s/nm.Through x-ray photoelectron spectroscopy (XPS) quantitative analysis, the change of the present embodiment thin-film material
It is (GS) to learn composition formula94.25C5.75。
Comparative example 1
Single layer Ge is prepared in this comparative example 115Sb85Phase change film material.
Ge15Sb85Nano film material is made using magnetron sputtering method；High-purity argon gas is passed through when preparation as sputter gas,
Sputtering pressure is 0.5pa, Ge15Sb85Target uses DC power supply, power 30W.Specific preparation method includes the following steps：
1. SiO2/Si (100) substrate that size is 1cm*1cm is chosen, cleaning surface, the back side, removal dust granule, organic
And inorganic impurity.
A) SiO2/Si (100) substrates and sheet glass are used to the power ultrasonic of 40w in acetone soln 10 minutes, deionization
Water rinses；
B) by treated substrate in ethanol solution with the power ultrasonic of 40w 10 minutes, deionized water is rinsed, high-purity
Surface and the back side are done in N2 air-blowings, obtain substrate to be sputtered.
2. preparing Ge using d.c. sputtering method15Sb85Prepare before film.
A) Ge is installed15Sb85The purity of target, target reaches 99.99% (atomic percent), and base vacuum is evacuated to
10-4Pa；
B) it uses high-purity Ar gas as sputter gas, sets Ar steady air currents and be adjusted to as 10sccm, and by sputtering pressure
The distance 150mm of 0.5pa, target and substrate；
C) DC sputtering power power is set as 30W.
3. the method for magnetron sputtering prepares Ge15Sb85Nano phase change thin-film material.
A) space base support rotates to Ge15Sb85Target position opens Ge15Sb85The baffle of target carries out pre-sputtering 5-10min, cleans target
Material surface；
b)Ge15Sb85After the completion of target surface cleaning, Ge is closed15Sb85The baffle of target rotates to substrate to be sputtered
Ge15Sb85Target position opens Ge15Sb85Target position baffle starts to sputter Ge according to the sputtering time of setting15Sb85Film.Work as sputtering
When time is 1min, the Ge that is prepared15Sb85Film thickness is 20nm or so, is measured for X ray reflection rate；When sputtering
Between when being 10min, the Ge that is prepared15Sb85Film thickness is 200nm or so, for In-situ resistance rate annealing measurement and AFM
It measures.Film thickness is controlled by sputtering time, and the sputter rate of film is 3s/nm.
Comparative example 2
As described in the background art, there are 10% vacancy in the crystalline state of conventional phase change material GST, thus before phase change after
Density contrast can reach 8% or more.Liangcai Wu et al. are shown by X ray reflection rate measurement by GST phase transformation materials
When adulterating C content to 2.9% in material, the variable density after before phase change can be reduced to 4.45% from 9.65%.In mechanism side
Face, first-principles calculations of the Liangcai Wu et al. based on Density functional the result shows that, the C atoms of incorporation tend to replace
For Te atoms, the spatial continuity of ABAB rings (A represents Ge or Sb atoms, and B represents Te atoms) is destroyed, increases tetrahedron Ge atoms
Ratio reduce the variable density before and after material to improve the amorphous stability of GST.
And for the present invention Ge-Sb materials for, in crystalline state and be not present intrinsic vacancy, therefore before phase change after density
Variation is originally just smaller than GST, 6% or so.And the present invention C doping contents concentration gradient from 2.66% to
5.75%, it can realize and variable density is down to 1.79% from 6.24%.And in terms of mechanism, in Ge-Sb phase-change materials not
There are sulphur series elements Te, therefore C incorporations influence the GST different froms that the mechanism of Ge-Sb crystallization process should be adulterated with C, need to use
Experiment and calculating research are explored.And further investigations have shown that, in Ge-Sb-C phase-change materials, C atoms are by being entrained in
It in interstitial void, and forms tetrahedron center in amorphous state and improves atom packing efficiency, to the density after reduction before phase change
Variation.
By (GS) of above-described embodiment 1, embodiment 2 and embodiment 397.34C2.66、(GS)95.02C4.98、(GS)94.25C5.75With
The GS phase change film materials of comparative example 1 are tested, and obtain the front and back X ray reflection rate of each phase change film material annealing with incidence
The diffraction curve at angle such as Fig. 1；By (GS) of above-described embodiment 1, embodiment 2 and embodiment 397.34C2.66、(GS)95.02C4.98、
(GS)94.25C5.75It is tested with the GS phase change film materials of comparative example 1, obtains using thickness before and after each phase change film material annealing
The volume (density) of characterization changes the curve such as Fig. 2 changed with C doping contents.By above-described embodiment 1, embodiment 2 and embodiment 3
(GS)97.34C2.66、(GS)95.02C4.98、(GS)94.25C5.75It is tested, is obtained each with the GS phase change film materials of comparative example 1
The In-situ resistance rate of phase change film material and relation curve such as Fig. 3 of annealing temperature；With first-principles calculations when C doping contains
Bond distance, bond angle and the ligancy situation such as Fig. 4 for the amorphous state Ge-Sb-C that amount is 5%；With first-principles calculations when C is adulterated
The super born of the same parents' model such as Fig. 5 for the amorphous state Ge-Sb-C phase-change materials that content is 5%；Contained with the different C doping of first-principles calculations
Formational situation such as Fig. 6 of C chains in the Ge-Sb-C phase-change storage materials of amount.The testing result of Fig. 1-Fig. 6 is as follows：
Fig. 1 is (GS) of the invention97.34C2.66、(GS)95.02C4.98、(GS)94.25C5.75With the GS phase-change thin films of comparative example 1
X ray reflection rate before and after anneal of material with incidence angle diffraction curve.Wherein, the deposition film that magnetron sputtering obtains is non-
Crystalline state, after carrying out X ray reflection rate test, amorphous nano phase change film carries out annealing 10min at 250 DEG C.After annealing
Crystalline state nano phase change film carry out the measurement of X ray reflection rate again, obtained by fitting and compare the close of the front and back film of annealing
Degree and thickness change.The film measured for X ray reflection rate is single thin film of the thickness in 20nm or so, and film
Surface roughness is 1nm or so, to meet test request.Can with it is seen in fig. 1, that when with one sheet of film annealing crystallization it
Afterwards, critical angle and the corresponding angle of reflection of maximum intensity are deviated toward high angle, it is meant that the density of film increases, and thickness reduces
(volume reduction).And according to the film thickness of X ray reflection rate and density measurement as a result, embodiment 1, embodiment 2 and embodiment 3
(GS)97.34C2.66、(GS)95.02C4.98、(GS)94.25C5.75It is preceding corresponding non-with the GS thin-film materials annealing for comparative example 1
Crystalline state density is respectively 6.15g/cm3、6.11g/cm3、6.07g/cm3And 6.19g/cm3, embodiment 1, embodiment 2 and embodiment
3 (GS)97.34C2.66、(GS)95.02C4.98、(GS)94.25C5.75It anneals at 250 DEG C with the GS thin-film materials for comparative example 1
Corresponding crystalline state density is respectively 6.49g/cm afterwards3、6.35g/cm3、6.27g/cm3And 6.58g/cm3, embodiment 1, embodiment 2
With (GS) of embodiment 397.34C2.66、(GS)95.02C4.98、(GS)94.25C5.75The front and back variable density difference of thin-film material annealing
It is 5.53%, 3.89%, 3.29%, the variable density before and after the GS Thin-film anneals of comparative example 1 is 6.24%.It can be seen that after mixing C
Ge-Sb-C films can effectively reduce the variable density before and after material phase transformation, reduce the stress generated in phase transition process, to
It helps to ensure that PCRAM phase change mediums layer and upper/lower electrode reliable contacts, improves device cycle number and service life.
Fig. 2 is measured (GS) of the invention with AFM97.34C2.66、(GS)95.02C4.98、(GS)94.25C5.75With comparative example 1
The front and back volume (density) characterized with thickness of GS phase change film materials annealing changes the change curve with C content.For each C
The film of doping concentration, it is (close come the volume for characterizing sample with thickness change after the front and back film thickness for respectively surveying 12 points of annealing
Degree) variation, 12 variable densities are averaged (Δ ρtrans).Figure it is seen that embodiment 1, embodiment 2 and embodiment 3
(GS)97.34C2.66、(GS)95.02C4.98、(GS)94.25C5.75The front and back variable density of thin-film material annealing is respectively 4.89%,
3.80%, 1.79%, the variable density before and after the GS Thin-film anneals of comparative example 1 is 5.16%, the result and X-ray of variable density
The result of reflectivity is consistent, it is seen that mixes C really and can effectively reduce the volume change in phase transition process, improve the cycle time of device
Number and service life.
Fig. 3 is (GS) of the invention97.34C2.66、(GS)95.02C4.98、(GS)94.25C5.75With the GS phase-change thin films of comparative example 1
The In-situ resistance rate and annealing temperature relational graph of material, correspond to GeSb, (GS) respectively from left to right97.34C2.66、(GS)95.02C4.98
(GS)94.25C5.75.The In-situ resistance rate of each phase change film material and the relation test method of temperature are as follows：It is annealed by one
The external M1500 tester of stove has built the test system of an in situ measurement resistance v. temperature.Annealing furnace passes through thermocouple pair
Film sample is heated, and heating rate is 5 DEG C/min, while carrying out annealing operation under vacuum conditions.It is used while heating
M1500 measures its resistance, and is converted into resistivity according to structural parameters.By Fig. 3, when less than phase transition temperature, all films are equal
For high-impedance state, show that all thin-film materials are amorphous state.As temperature gradually rises, film resiativity gradually slowly reduces,
When it reaches phase transition temperature, film resiativity drastically declines, and is held essentially constant after reaching a certain resistivity value, shows thin
The phase structure of membrane material is converted into the trigonal crystal structure of the typical Sb atoms of crystalline state from amorphous state.As shown in Figure 3：First, with
The increase of C content is mixed, the phase transition temperature of thin-film material has been increased to 210 DEG C from 175 DEG C in comparative example 1, has shown phase-change material
The thermal stability of Ge-Sb-C is significantly improved；Second, with the increase for mixing C content, the crystalline resistance rate of phase change film material
Increase, effectively reduces RESET power consumptions；Third, with the increase for mixing C content, phase change film material Ge-Sb-C amorphous state high resistants
Order of magnitude comparison is kept between crystalline state low-resistance, is conducive to the signal-to-noise ratio for improving PCRAM, is improved its anti-interference ability.
Fig. 4 is with the bond distance of the amorphous state Ge-Sb-C for being 5% when C doping contents of first-principles calculations, bond angle and to match
Digit situation.It can be found that the bond distance of C and Sb is obviously (Fig. 4 a) shorter than the bond distance of Ge-Ge, Ge-Sb and Sb-Sb；And C is former
Son is formed by bond angle close to 109 ° (Fig. 4 b)；It is found according to ligancy result of calculation, the ligancy of C atoms is 4 (Fig. 4 c), card
It is bright in Ge-Sb-C, the C atoms of incorporation form tetrahedron center, more stable chemical bond are formed with Ge/Sb, as used in Fig. 5
Shown in super born of the same parents' model of the amorphous state Ge-Sb-C phase-change materials for being 5% when C doping contents of first-principles calculations.It can be seen that C
Doping improves the deposition efficiency of amorphous atomic, to the variable density after reducing before phase change.
Fig. 6 is in the present invention with C in the Ge-Sb-C phase-change storage materials of the different C doping contents of first-principles calculations
The formational situation of chain.It can be found that when C doping contents are 3% (Fig. 6 b), C atoms are randomly dispersed in the week of Ge and Sb atoms
It encloses, and C atoms do not form chemical bond between each other；When C doping contents are 6% (Fig. 6 c), a small amount of C can be obviously observed
The formation of chain, but most of C atoms still with Ge/Sb bondings；And work as C doping contents in 10% or so (Fig. 6 d), it can be found that greatly
Part C atoms are in key and form apparent C chains.The formation of C chains can lead to the precipitation of C in phase transition process, influence following for device
Ring performance, and this with the purpose of the present invention is disagree.Therefore, the atom doped contents of currently preferred C are 2%-
6% or so doping concentration, to achieve the purpose that variable density after reducing before phase change and keep Ge-Sb other materials performances.
As it will be easily appreciated by one skilled in the art that the foregoing is merely illustrative of the preferred embodiments of the present invention, not to
The limitation present invention, all within the spirits and principles of the present invention made by all any modification, equivalent and improvement etc., should all include
Within protection scope of the present invention.
Claims (10)
1. a kind of Ge-Sb-C phase-change storage materials, which is characterized in that its chemical composition general formula is (GeiSbj)100-xCx, wherein x,
I, j are atomic percent, wherein 0 ＜ x ＜, 15,0 ＜ i≤50,50≤j ＜ 100, i+j=100.
2. phase-change storage material as described in claim 1, which is characterized in that 0 ＜ x ＜, 6,0 ＜ i≤20,80≤j ＜ 100, i+
J=100.
3. phase-change storage material as claimed in claim 1 or 2, which is characterized in that C in the Ge-Sb-C phase-change storage materials
Atom is present in Ge-Sb interstitial voids, and forms chemical bond with Ge-Sb.
4. phase-change storage material as claimed in claim 1 or 2, which is characterized in that the Ge-Sb-C phase-change storage materials are
Ge-Sb-C phase change film materials.
5. phase-change storage material as claimed in claim 4, which is characterized in that the thickness of the film is 20-200nm.
6. phase-change storage material as claimed in claim 1 or 2, which is characterized in that the Ge-Sb-C phase-change storage materials pass through
The incorporation content of C is controlled to control the phase transition temperature and resistivity of the phase-change storage material.
7. phase-change storage material as claimed in claim 1 or 2, which is characterized in that the height of the Ge-Sb-C phase-change storage materials
The resistivity of resistance state is at least 100 times of low resistance state.
8. the preparation method of the phase-change storage material as described in claim 1-7 any one, which is characterized in that it is splashed for magnetic control
Penetrate method, chemical vapour deposition technique, atomic layer deposition method, galvanoplastic or electron-beam vapor deposition method.
9. preparation method as claimed in claim 8, which is characterized in that it is magnetron sputtering method, and specific magnetron sputtering mode is
Any one in following four mode：(1) C, Ge and Sb target co-sputtering；(2) C and GeiSbjCosputtering；(3) after C doping
GeiSbjAlloys target sputters and graphite flake is directly placed at Ge by (4)iSbjSputtering is doped on alloy target material.
10. application of the Ge-Sb-C phase-change storage materials in phase transition storage as described in claim 1-7 is any.
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